If you’re like me, you cringe when you hear someone on reality TV say, “Don’t take it personal.” At that moment, I fear that it will catch on like wildfire across the world and this will be adopted as a new language rule. 

The correct way to express this sentiment is: “Don’t take it personally.” 

Personal is an adjective that describes a noun. Personally is an adverb used to describe an action. 

Correct: Paul Giamatti’s character in Sideways has a personal vendetta against Merlot wine.

Correct: Because he failed to water my plant while I was away, I found him to be personally responsible for it dying.

Correct: Don’t take it personally. 

The same can be applied to serious and seriously and other adjectives and adverbs.